Apparatus for receiving compressional waves



Nov. 28, 1939. w. KALLMEYER Armnxrus FOR RECEIVING COMPRESSIONAL WAVES Filed Dec. 8, 1953 INVENTOR.

Wi/he lm Ka/lmeyer BY m WPQf hi ATTORNEY.

Patented Nov. 28, 1939 UNITED STATES APPARATUS ron RECEIVING. coMrREs- SIONAL WAVES Wilhelm Kallmeyer, Bremen, Germany, assignor to Submarine Signal Company, Boston, Mass.,

a corporation of Maine Application December s, 1933, Serial no. 701,508

In Germany March 29, 1933 2 Claims.

The present invention relates to a receiver for compressional waves particularly foruse in submarine signaling. More particularly the present invention relates to submarine sound receivers in 5 which the piezo-electric effect of bodies, such as Rochelle-salt crystals, is employed.

In submarine signaling systems in which piezoelectric crystals have been used as receivers, the receiver must be mounted in close proximity to the water. Such receivers are usually mounted in the skin of a ship, projected through a tube beneath the ship or suspended in a tank at the bottom of the ship. The indicating devices to which the energy from the receiver is conducted are usually, on the other hand, mounted in the upper part of the vessel, for example, in the wheel house.

Amplifiers are in practically all cases required and these have in the past been mounted in the 20 indicator box or adjacent to the indicator. The

cable connecting the amplifier with the receiver is consequently quite long and has a large capacity which interferes with the eflicient operation of the system. The present invention avoids this 25 difliculty.

By means of the present invention the sensitivity of the system is substantially increased. Furthermore, by virtue of the present invention the electric and magnetic disturbances which are 80 picked up by the cable bear a much smaller ratio to the useful signaling energy. According to the present invention the first vacuum tube of the amplifier is mounted in the immediate proximity and preferably in the same housing with the 35 piezo-electric receiving body.

The invention may be better understood with reference to the accompanying drawing which shows a receiving device constructed according to the present invention.

40 A piezo-electric body. for example, a Rochellesalt crystal 3, is mounted in a housing E and is pressed against a piston diaphragm A by means of a pressure device H. The diaphragm A is thus firmly pressed against the crystal B and 45 possesses no undesired natural frequency. The rim E1 of the diaphragm is constructed to form a portion of the walls of a cylindrical housing. Screwed to the portion E1 is a cylinder E which forms an extension of the walls of the housing.

50 Within the housing and in the immediate vicinity of the piezo-electric crystal B there is mounted a vacuum tube F supported by resilient material, for example, sponge rubber D and D1, in order to prevent undesired vibrations.

55 The crystal is insulated from the housing and the pressure arrangement H by means of layers C and C1 of insulating material. Electric energy is conducted from the crystal through the electrodes J1 and J2, built up of tin foil and cemented to the surfaces of the crystals, and the leads K and K1 to the vacuum tube F which forms the 6 first tube of the amplifier. The lower end of the housing is closed by a disc L through which cable M connects the device to the amplifier. The cable M is made watertight by means of the gasket G and a cap N. 10

It is understood that more than one vacuum tube of the amplifier may be mounted within the casing containing the crystal or in a separate casing in the immediate vicinity of the crystal. It is, however, suflicient to place a single tube within the casing and the remainder of. the amplifier at some remote point convenient for operation. The remainder of the amplifier has not been shown since its particular design forms no part of the present invention with the exception that the tube shown is intended to form the first tube thereof. I

Having now described my invention, I claim:

1. A submarine sound receiver comprising a cylindrical casing having a diaphragm at one end thereof, a plezo-electric crystal positioned in contact with said diaphragm, a plate positioned against the surface of said crystal opposite the surface of contact with the diaphragm, means closing said crystal in a chamber at the end of said casing, said means being threaded in said casing and adapted to exert pressure on said plate, a second chamber in the other part of said casing, means closing said second chamber at the end of said cylinder, said chamber being provided with a supporting shelf, a vacuum tube amplifier supported on said shelf and means positioned Just below the means closing said first chamber for securing'said vacuum tube firmly in position. 40

2. A submarine sound receiver comprising a cylindrical casing having. an internally extending flange within the casing, partition means threaded to said flange to form two compartments therein, means closing one end of the casing forming a diaphragm at said end, means resting on said partition means, a piezo-electric crystal positioned on said last means and adjusted to contact the inner face of the diaphragm, a vacuum tube and means for positioning the vacuum tube within the second compartment including means positioned between the partition and the vacuum tube for firmly holding the vacuum tube in place and means attached at the other end of the casing for closing the same.

WILHELM KALLMEYER. 

